• Journal of Bio-Environment Control
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• v.17 no.3
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• pp.197-203
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• 2008

This study was performed to check the structural safety of modified 1-2W Greenhouses to be utilized fur growing Paprika. This type of greenhouse was derived from being remodeled by enhancing the column height of conventional 1-2W type greenhouses. According to the results of structural analysis performed by SAP-2000, there was not significant change in critical snow depth in spite of increasing the column height of 1.2 m by welding. But the critical wind velocities were shown to be $26.0\sim4l.0m/s$, which were $3\sim18%$ lower wind velocities compared with those critical velocities estimated for typical type of 1-2W greenhouse. Under the wind loads, those maximum section forces such as shear force, axial force, and bending moment, together with the deformed frame shape of strained greenhouse, were almost similar in both typical type and modified type. Maximum bending moment of column was found at eave's height of column on windward side. Under the snow loads, those maximum section forces such as shear farce, axial force, and bending moment, together with the deformed frame shape of strained greenhouse, were almost similar in both typical type and modified type. Maximum section forces except axial force was found at eave's height of column. Maximum axial force was found at inner column. Soil bearing capacity together with the total foundation resistance against wind upheaval was found to be consistently safe enough to resist to both wind load and snow load.

• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.2
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• pp.83-94
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• 2004

The purpose of this study was to compare the distributing pattern of stress according to the types of occlusal load on the finite element models of the splinted implant prostheses. The finite element model was designed with the parallel placement of two fixtures ($4.0mm{\times}11.5mm$) on mandibular first and second molars. The cemented crowns for mandibular first and second molars were made. Three-dimensional finite element model was created with the components of the implant, surrounding bone and cemented crowns. Two types of occlusal load, the point load and the surface load within 0.5 mm radius circle, were applied to the finite element models with 200N magnitude in axial(along the long axis of the implant and oblique(angulation of $30^{\circ}$ to the long axis) directions perpendicular to cuspal incline. Loads were positioned from the center of central fossa and to distance of 2 mm and 4 mm apart from the center of central fossa. Von-Mises stresses were recorded and compared in the fixtures and sections. The results were as following : 1. Under axial loading at the central fossa, the stress was distributed along the fixture except for the apical portion, not relative to both point & surface contacts. 2. With offset distance increasing, the highest stresses were concentrated in the neck portion of the fixture. 3. The maximum von Mises stress under the oblique load was greater than that under the axial load. 4. Under the oblique load, the highest stress were concentrated in the buccal side and lingual neck portion of the fixture with offset distance increasing. The results had a tendency to increase the stress on the neck portion of fixture with the offset and oblique loads increasing. The design of occlusal scheme should be allowed to distribute stress axially in maximum intercuspation and to decrease the angulation of cuspal incline.

• Geomechanics and Engineering
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• v.17 no.4
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• pp.393-403
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• 2019

The cycling impact test of red sandstone soil under different axial pressure and different impact loads are conducted to reveal the mechanical properties and energy consumption mechanism of red sandstone soil with static-dynamic coupling loading. The results show that: Under the action of different axial pressure and different impact loads, the peak stress of the specimen increases, and then tends to be stable with the times of impact. With the increase of impact times, the specific energy absorption value of the red sandstone soil specimen is increased first and then gentle development trend. When the impact loads are certain, the larger the axial pressure is, the smaller the peak value of energy absorption, which indicates that the energy utilization rate is not high under the condition of large axial pressure. Through the analysis of energy utilization, it is found that the smaller the impact load, the higher the energy utilization rate. The greater the axial pressure, the lower the energy utilization rate. when the axial pressure is large, the impact loads corresponding to the maximum values of reflectivity, transmissivity and absorptivity are the same. The relationship between reflectivity and transmissivity is negatively correlated.

• Steel and Composite Structures
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• v.21 no.3
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• pp.605-628
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• 2016

The energy absorption characteristics of diamond core sandwich cylindrical columns under axial crushing process depend greatly on the amount of material which participates in the plastic deformation. Both the single-objective and multi-objective optimizations are performed for columns under axial crushing load with core thickness and helix pitch of the honeycomb core as design variables. Models are optimized by multi-objective particle swarm optimization (MOPSO) algorithm to achieve maximum specific energy absorption (SEA) capacity and minimum peak crushing force (PCF). Results show that optimization improves the energy absorption characteristics with constrained and unconstrained peak crashing load. Also, it is concluded that the aluminum tube has a better energy absorption capability rather than steel tube at a certain peak crushing force. The results justify that the interaction effects between the honeycomb and column walls greatly improve the energy absorption efficiency. A ranking technique for order preference (TOPSIS) is then used to sort the non-dominated solutions by the preference of decision makers. That is, a multi-criteria decision which consists of MOPSO and TOPSIS is presented to find out a compromise solution for decision makers. Furthermore, local and global sensitivity analyses are performed to assess the effect of design variable values on the SEA and PCF functions in design domain. Based on the sensitivity analysis results, it is concluded that for both models, the helix pitch of the honeycomb core has greater effect on the sensitivity of SEA, while, the core thickness has greater effect on the sensitivity of PCF.

• Steel and Composite Structures
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• v.22 no.2
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• pp.429-448
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• 2016

This paper presents a finite element (FE) model for predicting the behaviour of steel column-column connections under axial compression and tension. A robustness approach is utilised for the design of steel column-column connections. The FE models take into account for the effects of initial geometric imperfections, material nonlinearities and geometric nonlinearities. The accuracy of the FE models is examined by comparing the predicted results with independent experimental results. It is demonstrated that the FE models accurately predict the ultimate axial strengths and load-deflection curves for steel column-column connections. A parametric study is carried out to investigate the effects of slenderness ratio, contact surface imperfection, thickness of cover-plates, end-plate thickness and bolt position. The buckling strengths of steel column-column connections with contact surface imperfections are compared with design strengths obtained from Australian Standards AS4100 (1998) and Eurocode 3 (2005). It is found that the column connections with maximum allowable imperfections satisfy the design requirements. Furthermore, the steel column-column connections analysed in this paper can be dismantled and reused safely under typical service loads which are usually less than 40% of ultimate axial strengths. The results indicate that steel column-column connections can be demounted at 50% of the ultimate axial load which is greater than typical service load.

• The Journal of Korean Physical Therapy
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• v.12 no.3
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• pp.455-467
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• 2000

The purpose of this study was to analyse the effects of disc degeneration on the biomechanical behaviors of the intervertebral disc in term of axial displacement, intradiscal pressure. disc bulge at the 1.4-1.5 functional spinal unit(FSU). The degeneration is divided 4 grade by initial intradiscal pressure: normal: 135kPa. mild: 107kPa. moderate: 47kPa, severe: 15kPa, The predicted results were follows: 1. The magnitude of the bulge is found to be maximum at the anterior, minimum at the postero-lateral portion. The bulge of lateral, postero-lateral is found to be maximum in severe grade. followed by moderate. mild, normal grade. 2. Tho displacement was increased with increasing compressive load in all four grades.'rho stiffness of disc was found to be reduced by progressing from normal to severe grade. 3. The intradiscal pressure was increased nearly linearly with increasing compressive load in normal and mild grade. But the increasing rate in moderate and severe grade was showed apparently different from nomal and mild grade. Specially, it was increased very slightly in severe grade. In conclusion, decreased intradiscal pressure resulted in increase of axial displacement and disc bulge with compressive load increasing. these may compromise the nerve root impingement or irritation. Therefore posture and activities must be focus to reduce compressive load applied on the back or disc.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.409-429
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• 2006

In designing rock-socketed drilled shaft, bearing capacity evaluation is very important because the maximum values of base and side resistance are not generally mobilized at the same value of displacement, FHWA and AASHTO code suggest different ultimate bearing capacity formular according to rock type and shaft settlement. In domestic code suggest base resistance and side resistance can be added on condition that after confirming the result of field load test with axial load transfer test. This paper shows that static load test and hi-directional load test result analysis of deep rock-socketed drilled shaft in three different sites. Load-settlement curve, t-z, and q-w curve in rock-socketed part were calculated and compared. t-z curve in weathered and soft rock showed no deflection softening behavior in pretty large strain (about 2-3% of diameter). Ultimate resistance could be the summation of side resistance and base resistance in rock-socketed drilled shaft in domestic sites.

• Structural Engineering and Mechanics
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• v.47 no.4
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• pp.575-598
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• 2013

The study presents the results of an experimental program concerning the shear force transfer between reinforced concrete (RC) jackets and existing columns with damages. In order to investigate the effectiveness of the repair method applied and the contribution of each shear transfer mechanism of the interface. It includes 22 concrete columns (core) (of 24,37MPa concrete strength) with square section (150mm side, 500 mm height and scale 1:2). Ten columns had initial construction damages and twelve were subjected to initial axial load. Sixteen columns have full jacketing at all four faces with 80mm thickness (of 31,7MPa concrete strength) and contain longitudinal bars (of 500MPa nominal strength) and closed stirrups spaced at 25mm, 50mm or 100mm (of 220MPa nominal strength). Fourteen of them contain dowels at the interface between old and new concrete. All columns were subjected to repeated (pseudo-seismic) axial compression with increasing deformation cycles up to failure with or without jacketing. Two load patterns were selected to examine the difference of the behavior of columns. The effects of the initial damages, of the reinforcement of the interface (dowels) and of the confinement generated by the stirrups are investigated through axial- deformation (slip) diagrams and the energy absorbed diagrams. The results indicate that the initial damages affect the total behavior of the column and the capacity of the interface to shear mechanisms and to slip: a) the maximum bearing load of old column is decreased affecting at the same time the loading capacity of the jacketed element, b) suitable repair of initially damaged specimens increases the capacity of the jacketed column to transfer load through the interface.

• Journal of Korean Society of Steel Construction
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• v.13 no.4
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• pp.363-372
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• 2001

The objective of this study is to evaluate the $P-{\Delta}$ effect in the case of weak beam unbraced frames by experimental approach. To evaluate $P-{\Delta}$ effect, four specimens were tested under monotonic loading condition. The parameters of tests are the stiffness of column and the axial load ratio. The results show that the value of axial load affects frame stability because $P-{\Delta}$ effects promote the yielding of beam. The maximum lateral load increases in proportion to the increment of column stiffness and rotational stiffness of supports, The collapse mechanism of weak beam unbraced frames is stably formed in the condition of low axial load ratio. The $B_2$ factor of limit state design code does not properly consider the $P-{\Delta}$ effect in inelastic region.

• Advances in concrete construction
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• v.8 no.4
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• pp.335-349
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• 2019

To investigate the axial compressive performance of the recycled aggregate concrete (RAC) filled glass fiber reinforced polymer (GFRP) tube and profile steel composite columns, static loading tests were carried out on 18 specimens under axial loads in this study, including 7 RAC filled GFRP tube columns and 11 RAC filled GFRP tube-profile steel composite columns. The design parameters include recycled coarse aggregate (RCA) replacement percentage, profile steel ratio, slenderness ratio and RAC strength. The failure process, failure modes, axial stress-strain curves, strain development and axial bearing capacity of all specimens were mainly analyzed in detail. The experimental results show that the GFRP tube had strong restraint ability to RAC material and the profile steel could improve the axial compressive performance of the columns. The failure modes of the columns can be summarized as follow: the profile steel in the composite columns yielded first, then the internal RAC material was crushed, and finally the fiberglass of the external GFRP tube was seriously torn, resulting in the final failure of columns. The axial bearing capacity of the columns decreased with the increase of RCA replacement percentage and the maximum decreasing amplitude was 11.10%. In addition, the slenderness ratio had an adverse effect on the axial bearing capacity of the columns. However, the strength of the RAC material could effectively improve the axial bearing capacity of the columns, but their deformability decreased. In addition, the increasing profile steel ratio contributed to the axial compressive capacity of the composite columns. Based on the above analysis, a formula for calculating the bearing capacity of composite columns under axial compression load is proposed, and the adverse effects of slenderness ratio and RCA replacement percentage are considered.